Msgr Lucio Angel Vallejo Balda claimed in Vatican court trial that he was manipulated into handing over the documents.
The priest has said that he was intimidated into leaking the documents and manipulated by a female co-defendant, Francesca Chaouqui, that he claims he was romantically involved with.
Msgr Balda also admitted to giving another defendant in the trial around 87 passwords to access electronic documents as well email accounts in the Vatican.
He told the court that Francesca Chaouqui told him she was a spy for the Italian secret services, adding that he felt "compromised" and told the court at times he had felt like he was in "a situation with no way out."
The former Vatican employee added that he had received a threatening message from Francesca Chaouqui and her husband.
Francesca Chaouqui and Fr Vallejo Baldo were both part of a committee formed by the Pope in 2013 to stamp out corruption and reform the Vatican's finances.
Mrs Chaouqui has denied Msgr Balda's claims, and is suing Fr Balda for saying that they had sex and that she bullied him into releasing the documents.
The focus of the Holy See trial is around two books which accuse the Vatican of financial mismanagement, and argue that Pope Francis has significant internal opposition within the Vatican.
The two books were released in 2015, based on the leaked documents.
Five people, including the two Italian journalists who wrote them, are also on trial facing jail terms of up to eight years.
